Salesforce Development Tutorial (LWC): How to use Data Attributes to easily pass data from your component HTML template to your JavaScript Controller

What are Data Attributes and Why Should I Use Them?

Data attributes are a truly magical thing that will, at some point, get you out of some prickly situations as a front end developer. They are essentially a way of storing data on an html element so that when a JS event gets fired your JS controller can easily get access to the data on the HTML element that fired the event.

This is especially useful in scenarios where you want to use for:each templates to generate tables, tabs or whatever else on the screen.


How to use Data Attributes (Example Code and Explanation)

Using data attributes is easy peasy lemonnnnnnnnnnn squezzyyyyyyyy… I’m sorry, it just felt right. Seriously though, it’s easy. Let’s first take a look at how we setup our HTML Template to use data attributes on a button element.

<template>
<lightning-button onclick={getDataAttributes} label="Click Me Bruh" data-donkey="donkeysAreKewl" data-turtle="NinjaTurtles"></lightning-button>
</template>

You see those weird attributes on my element? The “data-donkey” and “data-turtle” attributes? Those are data attributes and as you can see they can be named anything! However they must be in this format: data-randomnameyouchoose. Anything can come after the “data-” when setting up the data attributes on your element (do make sure each attribute has a unique name though!). Pretty cool right? The best part comes next though! Let’s check out the JavaScript Controller’s getDataAttributes method.

import {LightningElement} from 'lwc';

export default class LwcDataAttributes extends LightningElement {
	getDataAttributes(event){
		console.log('This is the data set ::: ' + 
                JSON.stringify(event.target.dataset));
		console.log('This is the data set turtle ::: ' + 
                JSON.stringify(event.target.dataset.turtle));
	}
}

You see that console log that has the “event.target.dataset” value in it? That event.target.dataset produces a Map that houses all of your data attributes in it. The output looks like this:

{"donkey":"donkeysAreKewl","turtle":"NinjaTurtles"}

As you can see it’s a key value pair, the key is whatever you named your data attribute on the HTML Element (notice the data- is excluded however) and the value is whatever value you assigned to that element on your HTML Element.

Now, you may also noticed in the console log below that one that we have the “event.target.dataset.turtle”, this line directly accesses the “data-turtle” value so it will just output “NinjaTurtles”. Pretty niftyyyyy! If you used event.target.dataset.donkey you would get the “donkeysAreKewl” value.

And to be honest that’s really all there is to it, there is one other quick thing we should review though.


What is an Event and the Difference between event.target and event.currentTarget

Boy oh boy does this really confuse people, so let me break it down right quick. Whatever element has the JS event attached to it is the one sending the event parameter to your JS method when you trigger the event (for instance when you use an onclick JS event on an HTML element and then click it to invoke the JS method). THIS IS IMPORTANT! I say this because, it is… trust me, but more importantly you can get into some tricky situations with event.target and event.currentTarget.

The key difference here is that event.target is the TRUE TARGET OF YOUR CLICK! and event.currentTarget is the ELEMENT THAT FIRED THE JS EVENT!

Even if you’ve never done it, you can sometimes wrap multiple elements within a div, and that div is actually the one that houses the onclick event. If you click a button within that div, the button is the “event.target” and the div is the “event.currentTarget”. Be wary of this! If you start to see null values or values you don’t expect in your dataset in your JS controller, this is more than likely why! It has confused many a person (including myself), so just make sure you are paying close attention to which target you are using in your controller.


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Salesforce Development Tutorial (LWC): How to create Custom Lightning Web Component Utility Modules

Why create Utility Modules for Lightning Web Components?

If you’re asking this question, I have feeling you don’t often utilize utility modules (or utility classes) anywhere… so let me be the first to welcome you to this absolutely magical world of utilities. They will make your life easier, code updates simpler and your code base a lot less terrifying.

Utility modules are useful in LWC’s because they allow you to take code you commonly use (or may commonly use) between components and allow tons of different components to use that same code without re-writing it a bunch.

Here’s a simple example. Say you pull URL parameters in several different lightning web components and in all of those components you have the exact same method that parses the url and returns those parameters. Instead of adding that method to every single component and having to update that method any time your process for parsing URL parameters change, you could just make a javascript utility module to deal with it, import it into your components and just call that single javascript utility module everywhere you needed to parse URL parameters. In the end this greatly reduces your codebase and the difficulty updating your code in the future.

Maybe the above is still confusing, no worries, let’s check out an example that will hopefully clear any confusion up.


How to create a Utility Module

So to give you a little background on what we’re about to do, I would suggest a little light reading on ES6 Javascript Modules. This will give you a bit better understanding on how all this code I’m about to show you works. If you’re not as obsessive of a reader as me, don’t worry though, I’ll explain everything just a bit throughout the rest of this post.

The first thing we need to do is create an LWC and delete the html file that comes with it as well as all the pre-built code in the javascript file. You might be like wutttttttt??????? But no worries, with utility modules you won’t need them. I know it feels weird right now, but just trust ya boi for one sec.

Next let’s take a look at a very simple LWC module with some exports in it. The name of the below LWC is “util_module”. Knowing the below components name will be important in the near future (GitHub where this code is also available).

//DISCLAIMER: There are many different ways available in ES6 JS to export variables, functions and classes
//you can find out more about exports here: https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export

//How to export a variable and make it available when importing your module
//in other components
export const OPEN_STATUS = 'Open';

//How to export a method and make it available when importing your module
//in other components
export function showError(error) {
    return 'This is an error ' + error;
}

//How to export a class and make it available when importing your module
//in other components
export class util_class {

    newStatus = 'New';

    showConsoleLog(){
        console.log('This is the console log ::: ');
    }

}

So what is all that junk up there? It’s not all that complicated after you get familiar with it. Basically what you are seeing are a handful of ways to make things accessible in a javascript module. The key thing here is that “export” keyword. Placing the export keyword in front of a variable, function or a class will allow you to import them into other components. Which brings us to the next part of this lesson, “How tf do we use this utility module”. Let’s check that out.


How to Import/Use your LWC Utility Module

Alright my guys (and gals), let’s check out the code to import that adorable little utility class we made up there into one of our normal LWC’s .

import { LightningElement } from 'lwc';

//Importing in our javascript utility module. The import variable names (OPEN_STATUS, //showError, util_class)
//are the names of the exported variable, method and class in our util_module component
import { OPEN_STATUS, showError, util_class} from 'c/util_module';

export default class Demo_component extends LightningElement 
{
    openStatus;
    returnedError;
    newStatus;

    //The connectedCallback method runs on component load
    connectedCallback()
    {
        //assigning our imported OPEN_STATUS value to our local openStatus variable
        this.openStatus = OPEN_STATUS;

        //assigning our imported showError methods return value to our local returnedError 
        //variable 
        this.returnedError = showError('Tacos had an error');

        //assigning our imported class's newStatus variable to our local newStatus variable
        this.newStatus = new util_class().newStatus;

        //Calling our imported class's showConsoleLog method
        new util_class().showConsoleLog();
    }
}

You’re thinking one of two things right now. It’s either, “Whoa my guy, it’s really that easy?” or, “Idk wtf that mess means”. For the group in latter, let me help you get into the former group with a little bit of an explanation.

Near the top of our LWC you’ll notice this line:

import { OPEN_STATUS, showError, util_class} from 'c/util_module';

This statement is importing the this various things we marked with the “export” keyword in the util_module LWC we created above. You will notice that the OPEN_STATUS, showError and util_class all are the exact names of the things with the “export” statement next to them in the util_module LWC.

These OPEN_STATUS, showError and util_class imports now become accessible in your class via those keywords. So for instance when we do this assignment:

this.openStatus = OPEN_STATUS;

We are literally assigning the OPEN_STATUS variable value from our util_module LWC to our local openStatus variable. Pretty cool right? Hopefully this makes things a little clearer… maybe… If I’m lucky anyway.

And that’s really it everyone! If you have any questions feel free to ask. I typically respond pretty quick.


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Salesforce Development Tutorial: How to Setup Uncrustify to automatically format your code in Visual Studio Code

Why would you want to setup Auto Code Formatting?

Aside from the fact that it’s both magical and amazing, it also enables you to easily do a couple things:

1) If you get onboarded to a project with a horrific looking codebase with nightmarish formatting, you can fix that by running a single command on the entire thing to fix it. This saves you what would otherwise take dozens if not hundreds of hours of time

2) If you are on a large team of developers and you want your code to all look the same (at least on your commit to your codebase), you can create one code style configuration file and distribute it to the entire team for use. This way your code all looks and reads the same which makes everything just a little bit nicer to deal with.

There are other reasons but those are the two major ones I can come up with off the top of my head here, lol.


Why use Uncrustify for auto-code formatting?

I like Uncrustify for automatic code formatting because it has so many configuration options, 735 in fact! It allows you to configure how you like your code to look as opposed to many other popular auto-code formatting tools that are “opinionated” that don’t give you that flexibility.


How to Setup Uncrustify

To utilize Uncrustify with your Salesforce projects in Visual Studio Code you need to do the following (Github wiki is here):

1) Install Uncrustify locally on your machine. I would suggest installing it via a package manager like chocolatey or npm if you are using a windows machine (you may need to download npm or chocolatey if you haven’t already)

2) Install the Uncrustify Visual Studio Code plugin. Restart VS Code after installing it.

3) In Visual Studio Code press Ctrl + Shift + P to bring up the command palette and then type the following command: Preferences: Open Settings (JSON). This should bring up a JSON file with your VS Code settings.

4) Inside the settings.json file you opened in the last step, add the following lines:

"uncrustify.langOverrides": {
    "apex": "JAVA",
    "apex-anon": "JAVA"
},

"[apex]": {
    "editor.defaultFormatter": "LaurentTreguier.uncrustify"
 },

"[javascript]": {
    "editor.defaultFormatter": "LaurentTreguier.uncrustify"
}

5) Save your settings.json file

6) Press Ctrl + Shift + P to bring up the command palette again and enter the following command: Uncrustify: Create Default Config. After running this command you should see an uncrustify.cfg file in your VS Code project

7) Open the uncrustify.cfg file and update all your settings in it (This is just a nice UI with a ton of different options, so nothing complicated here). Make sure to hit the save button in the top right corner when you are done!

8) Once you finished open a file you would like to have code formatting done to and press Alt+Shift+F

And that’s it boiz and gurlz! Enjoy your auto-formatted code!


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Salesforce Development (LWC): How to Communicate between Aura Components and Lightning Web Components Using Custom Events and the Api Decorator

Why Would You Want to Communicate Between Component Types?

There are a bunch of reasons it’s beneficial to communicate between component types but the most common ones that I have found are the following:

1) You’re building a new component and realize you need functionality that only Aura Components support, but it’s a very small piece of the component. Instead of building the entire thing in an outdated and much less performant Aura Component, you build most of it in an LWC and just communicate to a small Aura component to do the function only it can do.

2) You’re staffed in an Aura heavy org and when you start building new things for the existing Aura components you should build them in LWC. You can easily do this, but you need to know how the communication channels work between component types.

Once you see how easy it is to communicate between components it’ll be much easier to switch to LWC’s to do development for everything moving forward.


How to Communicate from an LWC to an Aura Component

This is super simple but it’s confusing if you’ve never done it before. We’re basically just gonna create a custom event in our LWC and handle that event in the Aura Component. Let’s check out the code and then I’ll explain it a bit:

<!--This is the LWC HTML-->
<template>
    <lightning-input class="dataToSend" placeholder="Enter text to transfer">
    </lightning-input>
    <lightning-button variant="brand" label="Pass data to Aura Component" 
    onclick={communicateToAura} ></lightning-button>
</template>
//This is the LWC JS Controller
import {LightningElement} from 'lwc';

export default class LwcCommunication extends LightningElement
{
    //This method creates a custom event that dispatches itself.
    //The Aura component then handles this event
    communicateToAura()
    {
         console.log('Communicating to Aura ::: ');

         //We are grabbing the value from the lightning input field that has the dataToSend 
         //class
         let dataToSend = this.template.querySelector(".dataToSend").value;

        //We are creating a custom event named senddata and passing a value in the detail 
        //portion of the custom event
        const sendDataEvent = new CustomEvent('senddata', {
            detail: {dataToSend}
        });

        //Actually dispatching the event that we created above.
        this.dispatchEvent(sendDataEvent);
    }
}
<!--This is the Aura Component HTML-->
<aura:component description="Aura_Communication">
	<aura:attribute name="dataReceived" type="String"/>

	<!--The onsenddata is what handles the custom event we made in our LWC-->
	<c:lwc_Communication onsenddata="{!c.receiveLWCData}" aura:id="lwcComp" />
        <p>This is the data receieved from our LWC: {!v.dataReceived}</p>
</aura:component>
({
       //This is the Aura JS Controller
	
        //This method receives data from our LWC and sets the dataReceived
	//Aura attribute with the events dataToSend parameter (this is the name of the 
        //variable we send in the LWC)
	receiveLWCData : function(component, event, helper)
	{
	    component.set("v.dataReceived", event.getParam("dataToSend"));
	}
});

Alright so now that you’ve checked out the code let’s go over this just a lil bit. In the communicateToAura method above you can see that we create a CustomEvent object and we give it the name ‘senddata’, we also pass some data in the custom event by using the detail property of our Javascript custom event object.

Then in the Aura component’s html we can see that we import our lightning web component using this line:

<c:lwc_Communication onsenddata="{!c.receiveLWCData}" aura:id="lwcComp" />

You can see that when we import our lightning web component that we have an onsenddata event that calls a method in the Aura Components javascript controller called receiveLWCData. When you dispatch your senddata event in your lightning web component the Aura component handles it with the onsenddata event attached to the lightning web component.

Finally you can see that we get the data from the event that was passed to us in the receieveLWCData in the Aura Components JS controller. The most important part of the method is the event.getParam(“dataToSend”). You are grabbing the variable that you passed into the detail property of your CustomEvent object in your LWC. Let me put them side by side so you see exactly what I mean:

//LWC Custom Event code
const sendDataEvent = new CustomEvent('senddata', {
            detail: {dataToSend}
});

//Aura code
component.set("v.dataReceived", event.getParam("dataToSend"));

And believe it or not it’s really that simple. You have successfully passed data from your LWC to your Aura component. Now let’s figure out how to do this in reverse.


How to Communicate from an Aura Component to an LWC

Alright so how do we do the exact opposite of what we did above?? It’s pretty simple but we need to leverage the wonderful @api decorator for lightning web components to make this work as opposed to Aura event communication. Alright so let’s check out the code below and then I’ll go over it a bit more in detail:

<!--This is the LWC Template/HTML-->
<template>
	<p>This is the data received from the Aura Component: {dataReceived}</p>
</template>
//This is the LWC JS Controller
import {LightningElement, api, track} from 'lwc';

export default class LwcCommunication extends LightningElement
{
	//Tracked variables ensure that they are refreshed on the page when their values are
	//updated in the code
	@track dataReceived;

	//The api decorator makes this a public method that any component that houses this 
        //component can access/call
	@api receiveData(data)
	{
	    this.dataReceived = data;
	}
}
<!--Aura Component HTML-->
<aura:component description="Aura_Communication">

	<!--The onsenddata is what handles the custom event we made in our LWC-->
	<c:lwc_Communication aura:id="lwcComp" />

	<lightning:input aura:id="dataToPass" />

	<lightning:button label="Pass data to LWC" onclick="{!c.passDataToLWC}"/>
</aura:component>
({
        //This is the Aura Component JS Controller

	//This method sends out data to our LWC from the Aura component.
	passDataToLWC : function(component, event, helper)
	{
		let stringToSend = component.find("dataToPass").get("v.value");

		//We are calling the receieveData method in our Lightning Web Component here
		component.find("lwcComp").receiveData(stringToSend);
	}
});

Alright, so as you can see nothing super complicated just some weird stuff you may not be super comfortable with yet. There are two very important pieces to making the passage of data between components possible.

The first is the @api method in the LWC. The receiveData method has the @api decorator in front of it. This makes the method public available to its parent component regardless of what component type it is.

The second is the component.find(“lwcComp”).receiveData(stringToSend) line in the passDataToLWC method in the Aura Components Javascript controller. This is finding the lwc that we imported into our Aura Component by its aura:id and then calling the receiveData method in the LWC (the method with the @api decorator) and passing it data.

This is surprisingly simple thankfully, no weird hacky tricks necessary just a few lines of code and we’re all good to go! If any of this is super confusing please check out the video above. I go over every aspect of the code in great detail.


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Salesforce Development Books I Recommend

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